Bios 256 Exam 2 Ultimate Study Guide Updated
Questions And Correct Answers
Anatomy & Physiology IV With Lab
SECTION I
Respiratory System Anatomy & Physiology
Questions 1–10
Upper vs. Lower Respiratory Tract; Pulmonary Ventilation: Boyle's Law, Inspiratory-Expiratory
Muscles; Gas Exchange: Alveolar-Capillary Diffusion, Fick's Law; Oxygen Transport: Hemoglobin
Saturation, Oxygen-Hemoglobin Dissociation Curve, Bohr Effect; CO2 Transport:
Bicarbonate/Carbamino/Dissolved Forms; Respiratory Control: Medullary/Pontine Centers,
Chemoreceptor Regulation
1. During quiet inspiration, which muscles are the primary drivers of pulmonary
ventilation by increasing thoracic cavity volume?
A. Internal intercostals and abdominal muscles
B. Diaphragm and external intercostals
C. Scalene and sternocleidomastoid muscles
D. Internal obliques and transversus abdominis
Correct Answer: B. Diaphragm and external intercostals
Rationale: During quiet inspiration, the diaphragm contracts and flattens, increasing the
vertical dimension of the thoracic cavity, while the external intercostals elevate the ribs,
increasing the anteroposterior diameter. Internal intercostals (A) are used during forced
expiration. Scalene and sternocleidomastoid muscles (C) are accessory muscles used only during
forced inspiration. Abdominal and oblique muscles (D) are expiratory muscles. Boyle's Law
dictates that increasing thoracic volume decreases intrapulmonary pressure, drawing air
inward.
2. According to Fick's Law of diffusion, which factor increases the rate of gas exchange
across the alveolar-capillary membrane?
A. Increasing membrane thickness
B. Decreasing the surface area available for diffusion
C. Increasing the partial pressure gradient between alveoli and blood
D. Decreasing the solubility coefficient of the gas
Correct Answer: C. Increasing the partial pressure gradient between alveoli and blood
Rationale: Fick's Law states that the rate of diffusion is directly proportional to the surface
area, the partial pressure gradient, and the gas solubility coefficient, and inversely proportional
to membrane thickness. Increasing the partial pressure gradient (C) directly increases diffusion
rate. Increasing membrane thickness (A) decreases diffusion rate. Decreasing surface area (B)
decreases diffusion rate. Decreasing solubility (D) decreases diffusion rate. This principle explains
why conditions like emphysema (reduced surface area) and pulmonary fibrosis (increased
thickness) impair gas exchange.
3. A patient's oxygen-hemoglobin dissociation curve shifts to the right. Which of the
following conditions would cause this shift, facilitating oxygen unloading at the tissues?
A. Decreased temperature, increased pH, decreased PCO2
B. Increased temperature, decreased pH (increased H+), increased PCO2
C. Increased 2,3-BPG, decreased temperature, increased pH
D. Decreased PCO2, increased pH, decreased 2,3-BPG
Correct Answer: B. Increased temperature, decreased pH (increased H+), increased PCO2
Rationale: A rightward shift of the oxygen-hemoglobin dissociation curve (Bohr effect) is caused
by conditions present in metabolically active tissues: increased temperature, decreased pH
, (increased H+ concentration), increased PCO2, and increased 2,3-BPG. These conditions reduce
hemoglobin's affinity for oxygen, facilitating oxygen unloading where it is needed most. Option A
describes a leftward shift (increased affinity). Option C is contradictory (2,3-BPG causes right
shift, but temperature and pH changes listed cause left shift). Option D describes a leftward shift.
4. Approximately 70% of carbon dioxide in the blood is transported in which form?
A. Dissolved CO2 in plasma
B. Carbaminohemoglobin bound to hemoglobin
C. Bicarbonate ion (HCO3−) in plasma
D. Carbonic acid within red blood cells
Correct Answer: C. Bicarbonate ion (HCO3−) in plasma
Rationale: Approximately 70% of CO2 is transported as bicarbonate ion (HCO3−) in plasma.
CO2 enters red blood cells, combines with water via carbonic anhydrase to form carbonic acid
(H2CO3), which dissociates into H+ and HCO3−. The HCO3− is then transported out of the RBC
into plasma via the chloride shift. Dissolved CO2 (A) accounts for about 7–10%.
Carbaminohemoglobin (B) accounts for about 20%. Carbonic acid (D) exists transiently and is not
a major transport form.
5. The central chemoreceptors located in the medulla oblongata are most sensitive to
changes in which stimulus?
A. Arterial PO2
B. Cerebrospinal fluid pH (indirectly via CO2)
C. Arterial potassium concentration
D. Cerebrospinal fluid sodium concentration
Correct Answer: B. Cerebrospinal fluid pH (indirectly via CO2)
Rationale: Central chemoreceptors in the medulla are most sensitive to changes in cerebrospinal
fluid (CSF) pH, which is determined primarily by arterial PCO2. CO2 readily crosses the blood-
brain barrier, where carbonic anhydrase converts it to carbonic acid, releasing H+ ions that
lower CSF pH and stimulate ventilation. Central chemoreceptors are not directly sensitive to
arterial PO2 (A); peripheral chemoreceptors (carotid and aortic bodies) respond to PO2.
Potassium (C) and sodium (D) are not primary stimuli for respiratory chemoreceptors.
6. The epiglottis is composed of which type of cartilage, and what is its primary function
during swallowing?
A. Hyaline cartilage; closes the glottis to prevent food entry into the trachea
B. Elastic cartilage; closes the glottis to prevent food entry into the trachea
C. Fibrocartilage; opens the glottis to allow air passage during swallowing
D. Elastic cartilage; opens the larynx to facilitate vocalization
Correct Answer: B. Elastic cartilage; closes the glottis to prevent food entry into the
trachea
, Rationale: The epiglottis is composed of elastic cartilage, which provides flexibility and the
ability to spring back into shape. During swallowing, the epiglottis deflects inferiorly to cover the
glottis, preventing food and liquid from entering the trachea. Hyaline cartilage (A) is found in the
tracheal rings and thyroid cartilage but is too rigid for the epiglottis. Fibrocartilage (C) is found
in intervertebral discs and pubic symphysis. The epiglottis closes (not opens) the airway during
swallowing, making both C and D incorrect.
7. Type II alveolar cells (pneumocytes) produce surfactant. Which of the following best
describes the primary physiological function of pulmonary surfactant?
A. Increases surface tension to prevent alveolar over-inflation
B. Decreases surface tension to prevent alveolar collapse (atelectasis)
C. Facilitates gas exchange by thinning the alveolar membrane
D. Produces mucus to trap airborne pathogens
Correct Answer: B. Decreases surface tension to prevent alveolar collapse (atelectasis)
Rationale: Pulmonary surfactant, composed of phospholipids (primarily
dipalmitoylphosphatidylcholine) and proteins, reduces surface tension at the air-water interface
within alveoli. By decreasing surface tension, surfactant prevents alveolar collapse (atelectasis)
during expiration, stabilizes alveolar size (Laplace's Law), and reduces the work of breathing.
Option A is the opposite effect. Surfactant does not thin the alveolar membrane (C) or produce
mucus (D); mucus is produced by goblet cells and submucosal glands in the conducting airways.
8. Select All That Apply: Which structures are part of the conducting zone of the
respiratory system? [SATA]
A. Terminal bronchioles
B. Respiratory bronchioles
C. Trachea and primary bronchi
D. Alveolar ducts
Correct Answer: A. Terminal bronchioles
Rationale: The conducting zone includes structures that transport air but do not participate in
gas exchange: nasal cavity, pharynx, larynx, trachea, primary bronchi, secondary and tertiary
bronchi, and terminal bronchioles (A, C). The respiratory zone includes structures where gas
exchange occurs: respiratory bronchioles (B), alveolar ducts (D), and alveoli. Therefore, A and C
are conducting zone structures, while B and D are respiratory zone structures.
9. A patient has a vital capacity (VC) of 4800 mL, a tidal volume (TV) of 500 mL, an
inspiratory reserve volume (IRV) of 3100 mL, and an expiratory reserve volume (ERV) of
1200 mL. What is the patient's residual volume (RV) if total lung capacity (TLC) is 6000
mL?
A. 600 mL
B. 1200 mL
C. 1800 mL
D. 2400 mL
Correct Answer: B. 1200 mL
Rationale: Total lung capacity (TLC) equals vital capacity (VC) plus residual volume (RV).
Therefore, RV = TLC − VC = 6000 mL − 4800 mL = 1200 mL. Residual volume is the air that
remains in the lungs after maximal expiration and cannot be measured directly by spirometry; it
must be calculated using body plethysmography or helium dilution. The VC calculation is
confirmed: TV + IRV + ERV = 500 + 3100 + 1200 = 4800 mL. The correct residual volume is 1200
mL.
10. The pharynx is divided into three regions. Through which region does both air and food
pass, making it a shared pathway for the respiratory and digestive systems?
A. Nasopharynx only
B. Oropharynx only
C. Laryngopharynx only
D. Both oropharynx and laryngopharynx
Questions And Correct Answers
Anatomy & Physiology IV With Lab
SECTION I
Respiratory System Anatomy & Physiology
Questions 1–10
Upper vs. Lower Respiratory Tract; Pulmonary Ventilation: Boyle's Law, Inspiratory-Expiratory
Muscles; Gas Exchange: Alveolar-Capillary Diffusion, Fick's Law; Oxygen Transport: Hemoglobin
Saturation, Oxygen-Hemoglobin Dissociation Curve, Bohr Effect; CO2 Transport:
Bicarbonate/Carbamino/Dissolved Forms; Respiratory Control: Medullary/Pontine Centers,
Chemoreceptor Regulation
1. During quiet inspiration, which muscles are the primary drivers of pulmonary
ventilation by increasing thoracic cavity volume?
A. Internal intercostals and abdominal muscles
B. Diaphragm and external intercostals
C. Scalene and sternocleidomastoid muscles
D. Internal obliques and transversus abdominis
Correct Answer: B. Diaphragm and external intercostals
Rationale: During quiet inspiration, the diaphragm contracts and flattens, increasing the
vertical dimension of the thoracic cavity, while the external intercostals elevate the ribs,
increasing the anteroposterior diameter. Internal intercostals (A) are used during forced
expiration. Scalene and sternocleidomastoid muscles (C) are accessory muscles used only during
forced inspiration. Abdominal and oblique muscles (D) are expiratory muscles. Boyle's Law
dictates that increasing thoracic volume decreases intrapulmonary pressure, drawing air
inward.
2. According to Fick's Law of diffusion, which factor increases the rate of gas exchange
across the alveolar-capillary membrane?
A. Increasing membrane thickness
B. Decreasing the surface area available for diffusion
C. Increasing the partial pressure gradient between alveoli and blood
D. Decreasing the solubility coefficient of the gas
Correct Answer: C. Increasing the partial pressure gradient between alveoli and blood
Rationale: Fick's Law states that the rate of diffusion is directly proportional to the surface
area, the partial pressure gradient, and the gas solubility coefficient, and inversely proportional
to membrane thickness. Increasing the partial pressure gradient (C) directly increases diffusion
rate. Increasing membrane thickness (A) decreases diffusion rate. Decreasing surface area (B)
decreases diffusion rate. Decreasing solubility (D) decreases diffusion rate. This principle explains
why conditions like emphysema (reduced surface area) and pulmonary fibrosis (increased
thickness) impair gas exchange.
3. A patient's oxygen-hemoglobin dissociation curve shifts to the right. Which of the
following conditions would cause this shift, facilitating oxygen unloading at the tissues?
A. Decreased temperature, increased pH, decreased PCO2
B. Increased temperature, decreased pH (increased H+), increased PCO2
C. Increased 2,3-BPG, decreased temperature, increased pH
D. Decreased PCO2, increased pH, decreased 2,3-BPG
Correct Answer: B. Increased temperature, decreased pH (increased H+), increased PCO2
Rationale: A rightward shift of the oxygen-hemoglobin dissociation curve (Bohr effect) is caused
by conditions present in metabolically active tissues: increased temperature, decreased pH
, (increased H+ concentration), increased PCO2, and increased 2,3-BPG. These conditions reduce
hemoglobin's affinity for oxygen, facilitating oxygen unloading where it is needed most. Option A
describes a leftward shift (increased affinity). Option C is contradictory (2,3-BPG causes right
shift, but temperature and pH changes listed cause left shift). Option D describes a leftward shift.
4. Approximately 70% of carbon dioxide in the blood is transported in which form?
A. Dissolved CO2 in plasma
B. Carbaminohemoglobin bound to hemoglobin
C. Bicarbonate ion (HCO3−) in plasma
D. Carbonic acid within red blood cells
Correct Answer: C. Bicarbonate ion (HCO3−) in plasma
Rationale: Approximately 70% of CO2 is transported as bicarbonate ion (HCO3−) in plasma.
CO2 enters red blood cells, combines with water via carbonic anhydrase to form carbonic acid
(H2CO3), which dissociates into H+ and HCO3−. The HCO3− is then transported out of the RBC
into plasma via the chloride shift. Dissolved CO2 (A) accounts for about 7–10%.
Carbaminohemoglobin (B) accounts for about 20%. Carbonic acid (D) exists transiently and is not
a major transport form.
5. The central chemoreceptors located in the medulla oblongata are most sensitive to
changes in which stimulus?
A. Arterial PO2
B. Cerebrospinal fluid pH (indirectly via CO2)
C. Arterial potassium concentration
D. Cerebrospinal fluid sodium concentration
Correct Answer: B. Cerebrospinal fluid pH (indirectly via CO2)
Rationale: Central chemoreceptors in the medulla are most sensitive to changes in cerebrospinal
fluid (CSF) pH, which is determined primarily by arterial PCO2. CO2 readily crosses the blood-
brain barrier, where carbonic anhydrase converts it to carbonic acid, releasing H+ ions that
lower CSF pH and stimulate ventilation. Central chemoreceptors are not directly sensitive to
arterial PO2 (A); peripheral chemoreceptors (carotid and aortic bodies) respond to PO2.
Potassium (C) and sodium (D) are not primary stimuli for respiratory chemoreceptors.
6. The epiglottis is composed of which type of cartilage, and what is its primary function
during swallowing?
A. Hyaline cartilage; closes the glottis to prevent food entry into the trachea
B. Elastic cartilage; closes the glottis to prevent food entry into the trachea
C. Fibrocartilage; opens the glottis to allow air passage during swallowing
D. Elastic cartilage; opens the larynx to facilitate vocalization
Correct Answer: B. Elastic cartilage; closes the glottis to prevent food entry into the
trachea
, Rationale: The epiglottis is composed of elastic cartilage, which provides flexibility and the
ability to spring back into shape. During swallowing, the epiglottis deflects inferiorly to cover the
glottis, preventing food and liquid from entering the trachea. Hyaline cartilage (A) is found in the
tracheal rings and thyroid cartilage but is too rigid for the epiglottis. Fibrocartilage (C) is found
in intervertebral discs and pubic symphysis. The epiglottis closes (not opens) the airway during
swallowing, making both C and D incorrect.
7. Type II alveolar cells (pneumocytes) produce surfactant. Which of the following best
describes the primary physiological function of pulmonary surfactant?
A. Increases surface tension to prevent alveolar over-inflation
B. Decreases surface tension to prevent alveolar collapse (atelectasis)
C. Facilitates gas exchange by thinning the alveolar membrane
D. Produces mucus to trap airborne pathogens
Correct Answer: B. Decreases surface tension to prevent alveolar collapse (atelectasis)
Rationale: Pulmonary surfactant, composed of phospholipids (primarily
dipalmitoylphosphatidylcholine) and proteins, reduces surface tension at the air-water interface
within alveoli. By decreasing surface tension, surfactant prevents alveolar collapse (atelectasis)
during expiration, stabilizes alveolar size (Laplace's Law), and reduces the work of breathing.
Option A is the opposite effect. Surfactant does not thin the alveolar membrane (C) or produce
mucus (D); mucus is produced by goblet cells and submucosal glands in the conducting airways.
8. Select All That Apply: Which structures are part of the conducting zone of the
respiratory system? [SATA]
A. Terminal bronchioles
B. Respiratory bronchioles
C. Trachea and primary bronchi
D. Alveolar ducts
Correct Answer: A. Terminal bronchioles
Rationale: The conducting zone includes structures that transport air but do not participate in
gas exchange: nasal cavity, pharynx, larynx, trachea, primary bronchi, secondary and tertiary
bronchi, and terminal bronchioles (A, C). The respiratory zone includes structures where gas
exchange occurs: respiratory bronchioles (B), alveolar ducts (D), and alveoli. Therefore, A and C
are conducting zone structures, while B and D are respiratory zone structures.
9. A patient has a vital capacity (VC) of 4800 mL, a tidal volume (TV) of 500 mL, an
inspiratory reserve volume (IRV) of 3100 mL, and an expiratory reserve volume (ERV) of
1200 mL. What is the patient's residual volume (RV) if total lung capacity (TLC) is 6000
mL?
A. 600 mL
B. 1200 mL
C. 1800 mL
D. 2400 mL
Correct Answer: B. 1200 mL
Rationale: Total lung capacity (TLC) equals vital capacity (VC) plus residual volume (RV).
Therefore, RV = TLC − VC = 6000 mL − 4800 mL = 1200 mL. Residual volume is the air that
remains in the lungs after maximal expiration and cannot be measured directly by spirometry; it
must be calculated using body plethysmography or helium dilution. The VC calculation is
confirmed: TV + IRV + ERV = 500 + 3100 + 1200 = 4800 mL. The correct residual volume is 1200
mL.
10. The pharynx is divided into three regions. Through which region does both air and food
pass, making it a shared pathway for the respiratory and digestive systems?
A. Nasopharynx only
B. Oropharynx only
C. Laryngopharynx only
D. Both oropharynx and laryngopharynx
